Centrin 1 ( human, 172 aa, MW, 19,570) plays a fundamental role in microtubule organizing center structure and function. Centrins, also known as caltractins, are a family present in the centrioles and pericentriolar lattice. Human centrin genes are CETN1, CETN2 and CETN3. Centrins are required for duplication of centrioles. They may also play a role in severing of microtubules by causing calcium-mediated contraction